/**
 * Copyright (c) 2012-2017, www.tinygroup.org (luo_guo@icloud.com).
 * <p>
 * Licensed under the GPL, Version 3.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.gnu.org/licenses/gpl.html
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.tinygroup.springmvc.util;

import org.springframework.http.MediaType;
import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.util.WebUtils;

import javax.servlet.http.HttpServletRequest;
import java.util.Iterator;
import java.util.List;

/**
 * Helper class for annotation-based request mapping. 基于注解的ServletMapping工具类
 *
 * @since 2.0
 */
public abstract class ServletAnnotationMappingUtils {

    /**
     * Check whether the given request matches the specified request methods.
     *
     * @param methods the HTTP request methods to check against
     * @param request the current HTTP request to check
     */
    public static boolean checkRequestMethod(RequestMethod[] methods,
                                             HttpServletRequest request) {
        if (!ObjectUtils.isEmpty(methods)) {
            boolean match = false;
            for (RequestMethod method : methods) {
                if (method.name().equals(request.getMethod())) {
                    match = true;
                }
            }
            if (!match) {
                return false;
            }
        }
        return true;
    }

    /**
     * Check whether the given request matches the specified parameter
     * conditions.
     *
     * @param params  the parameter conditions, following
     *                {@link org.springframework.web.bind.annotation.RequestMapping#params()}
     * @param request the current HTTP request to check
     */
    public static boolean checkParameters(String[] params,
                                          HttpServletRequest request) {
        if (!ObjectUtils.isEmpty(params)) {
            for (String param : params) {
                int separator = param.indexOf('=');
                if (separator == -1) {
                    if (param.startsWith("!")) {
                        if (WebUtils.hasSubmitParameter(request,
                                param.substring(1))) {
                            return false;
                        }
                    } else if (!WebUtils.hasSubmitParameter(request, param)) {
                        return false;
                    }
                } else {
                    String key = param.substring(0, separator);
                    String value = param.substring(separator + 1);
                    if (!value.equals(request.getParameter(key))) {
                        return false;
                    }
                }
            }
        }
        return true;
    }

    /**
     * Check whether the given request matches the specified header conditions.
     *
     * @param headers the header conditions, following
     *                {@link org.springframework.web.bind.annotation.RequestMapping#headers()
     *                RequestMapping.headers()}
     * @param request the current HTTP request to check
     */
    public static boolean checkHeaders(String[] headers,
                                       HttpServletRequest request) {
        if (!ObjectUtils.isEmpty(headers)) {
            for (String header : headers) {
                int separator = header.indexOf('=');
                if (separator == -1) {
                    if (header.startsWith("!")) {
                        if (request.getHeader(header.substring(1)) != null) {
                            return false;
                        }
                    } else if (request.getHeader(header) == null) {
                        return false;
                    }
                } else {
                    boolean negated = (separator > 0 && header
                            .charAt(separator - 1) == '!');
                    String key = !negated ? header.substring(0, separator)
                            : header.substring(0, separator - 1);
                    String value = header.substring(separator + 1);
                    if (isMediaTypeHeader(key)) {
                        List<MediaType> requestMediaTypes = MediaType
                                .parseMediaTypes(request.getHeader(key));
                        List<MediaType> valueMediaTypes = MediaType
                                .parseMediaTypes(value);
                        boolean found = false;
                        for (Iterator<MediaType> valIter = valueMediaTypes
                                .iterator(); valIter.hasNext() && !found; ) {
                            MediaType valueMediaType = valIter.next();
                            for (Iterator<MediaType> reqIter = requestMediaTypes
                                    .iterator(); reqIter.hasNext() && !found; ) {
                                MediaType requestMediaType = reqIter.next();
                                if (valueMediaType.includes(requestMediaType)) {
                                    found = true;
                                }
                            }

                        }
                        if (negated) {
                            found = !found;
                        }
                        if (!found) {
                            return false;
                        }
                    } else {
                        boolean match = value.equals(request.getHeader(key));
                        if (negated) {
                            match = !match;
                        }
                        if (!match) {
                            return false;
                        }
                    }
                }
            }
        }
        return true;
    }

    private static boolean isMediaTypeHeader(String headerName) {
        return "Accept".equalsIgnoreCase(headerName)
                || "Content-Type".equalsIgnoreCase(headerName);
    }
}
